Tehuano wind event

March 12th, 2022 |

Visible images from GOES-17 (left) and GOES-16 (right) [click to play animated GIF | MP4]

As a strong arctic cold front moved southward across the Gulf of Mexico and southern Mexico (surface analyses) on 12 March 2022, the cold air passed through the Chivela Pass and emerged as a Tehuano (or “Tehuantepecer“) gap wind that fanned outward across the Gulf of Tehuantepec. Visible images from GOES-17 (GOES-West) and GOES-16 (GOES-East) showed the narrow arc cloud that marked the leading edge of this gap flow (above).

GOES-16 True Color RGB images [click to play animated GIF | MP4]

True Color RGB images created using Geo2Grid from GOES-16 (above) and GOES-17 (below) showed the hazy signature of blowing dust/sand as it was transported off the south coast of Mexico and spread out across the Gulf of Tehuantepec.

GOES-17 True Color RGB images [click to play animated GIF | MP4]

ASCAT surface scatterometer winds from Metop-B and Metop-C (source) are shown below; gap winds emerging from the coast were in the 35-40 knot range at 1631 UTC.

ASCAT winds from Metop-B and Metop-C [click to enlarge]

Tehuano wind event

December 24th, 2020 |

GOES-16

Topography + GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) indicated that a strong arctic cold front (surface analyses) had plunged southward across Mexico, through the Chivela Pass, and emerged as a Tehuano (or “Tehuantepecer“) gap wind into the Gulf of Tehuantepec on 24 December 2020. Along the Gulf of Mexico coast, a few sites in Mexico reported blowing dust and/or blowing sand with onshore winds gusting to 40 knots.

GOES-16 True Color RGB images created using Geo2Grid (below) showed the hazy signature of blowing dust/sand as it was transported off the south coast of Mexico and spread out across the Gulf of Tehuantepec.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

===== 25 December Update =====

GOES-16 "Red" Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

On the following day, GOES-16 Visible images (above) showed that the leading edge of the gap wind flow — marked by a broad arc cloud — was approaching the ITCZ / Monsoon Trough in the Pacific Ocean. Ship reports of 30-35 knot winds were seen within the offshore flow — and ASCAT surface scatterometer winds revealed speeds as high as 44 knots.

GOES-16 True Color RGB images (below) showed the hazy signature of blowing dust from Mexico as it spread out across the Pacific Ocean.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

Aided by enhanced forward scattering during the morning hours, True Color RGB images from GOES-17 (GOES-West) showed the hazy signature of airborne dust from Mexico a bit better (below).

GOES-17 True Color RGB images [click to play animation | MP4]

GOES-17 True Color RGB images [click to play animation | MP4]

Tehuano gap wind event

February 27th, 2020 |

GOES-16 Visible (0.64 µm) images, with plots of surface reports (yellow), ASCAT winds (violet) and surface analyses (cyan) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with plots of surface reports (yellow), ASCAT winds (violet) and surface analyses (cyan) [click to play animation | MP4]

GOES-16 (GOES-East) Visible (0.64 µm) images (above) revealed a cloud arc which marked the leading edge of a Tehuano wind event — air behind a cold front plunged southward across the Gulf of Mexico during the previous day, crossed the mountains of Mexico through Chivela Pass (topography) , and emerged over the Pacific Ocean on 27 February 2020. Within the western portion of the gap wind flow, ASCAT winds speeds were as high as 32 knots at 1540 UTC — but closer to the coast the Ocean Prediction Center was initially forecasting an area of Storm Force winds (downgraded to Gale Force winds later in the day).

On a GOES-16 Visible image with plots of available NOAA-20 NUCAPS profiles (below), the location of one profile immediately offshore (Point 1) and another just ahead of the Tehauno cloud arc (Point 2) are highlighted.

GOES-16 Visible (0.64 µm) image, with plots of available NOAA-20 NUCAPS profiles [click to enlarge]

GOES-16 Visible (0.64 µm) image, with plots of available NOAA-20 NUCAPS profiles [click to enlarge]

A toggle between the NUCAPS profile immediately offshore (Point 1, at 15.39 N latitude 94.55 W longitude) and the profile just ahead of the Tehauno cloud arc (Point 2, at 7.29 N latitude 93.95 W longitude) is show below. Note that Total Precipitable Water values were 1.78 inches ahead of the cloud arc, compared to 1.16 inches immediately off the coast of Mexico where the dry gap winds were entering the Gulf of Tehuantepec.

NOAA-20 NUCAPS Temperature (red) and dewpoint (green) profiles for Point 1 and Point 2 [click to enlarge]

NOAA-20 NUCAPS Temperature (red) and dewpoint (green) profiles for Point 1 and Point 2 [click to enlarge]

In a comparison of Visible images from GOES-17 (GOES-West) and GOES-16 (GOES-East), haziness in the Gulf of Tehuantepec (best seen with GOES-16, due to a larger forward scattering angle) highlighted blowing dust that was being carried offshore by the strong gap winds.

“Red” Visible (0.64 µm) images from GOES-17 (left) and GOES-16 (right) [click to play animation | MP4]

GOES-16 True Color Red-Green-Blue (RGB) images created using Geo2Grid (below) provided a clearer view of the blowing dust plumes in the Gulf of Tehuantepec.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

VIIRS True Color RGB images from Suomi NPP and NOAA-20 as viewed using RealEarth are shown below.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

 

Tehuano wind event

March 5th, 2019 |

GOES-17 (left) and GOES-16 (right)

GOES-17 (left) and GOES-16 (right) “Red” Visible (0.64 µm) images, with plots of surface wind barbs (speed in knots) [click to play animation | MP4]

After a strong arctic cold front plunged southward across the US, the Gulf of Mexico, and then southern Mexico during the previous two days (surface analyses), GOES-17 (GOES-West) and GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) revealed the hazy plume of dust-laden Tehuano gap wind flow as it emerged from the southern coast of Mexico and spread southwestward across the Gulf of Tehuantepec and the Pacific Ocean on 05 March 2019. An image of the topography of southeastern Mexico shows the location of Chivela Pass, through which these gap winds flow. Along the Gulf of Mexico coast, surface winds gusted to 30 knots and higher after the cold front moved through Minatitlán/Coatzacoalcos International Airport (station identifier MMMT); off the Pacific coast, a ship in the Gulf of Tehuantepec reported a sustained wind speed of 30 knots at 12 UTC.

The GOES-16 Aerosol Optical Depth product (below) showed lightly enhanced AOD values toward the outer edges of the swath of Tehuano winds. Note the gap in the product during the afternoon hours, when large amounts of sun glint were present.

GOES-16 Aerosol Optical Depth product [click to play animation | MP4]

GOES-16 Aerosol Optical Depth product [click to play animation | MP4]

The GOES-16 Dust Detection product (below) did portray Low to Medium-Confidence areas of dust within the gap wind flow.

GOES-16 Dust Detection product [click to play animation | MP4]

GOES-16 Dust Detection product [click to play animation | MP4]

An overpass of the Suomi NPP satellite after 19 UTC provided numerous NUCAPS sounding profiles both within and outside of the perimeter of the Tehuano winds (below).

GOES-16 Aerosol Optical Depth product, with plots of available NUCAPS sounding profiles [click to enlarge]

GOES-16 Aerosol Optical Depth product, with plots of available NUCAPS sounding profiles [click to enlarge]

A comparison between a dry NUCAPS sounding (Point D) where the gap winds were first exiting the coast over the Gulf of Tehuantepec and a more “undisturbed” moist sounding (Point M) northwest of the gap wind flow is shown below. The dry air of the Tehuano wind flow was very shallow, but its presence could be seen in differences between the marine boundary layer dew point profile and the resulting height of the Lifting Condensation Level (LCL).

Comparison of Dry (D) and Moist (M) NUCAPS soundings [click to enlarge]

Comparison of Dry (D) and Moist (M) NUCAPS soundings [click to enlarge]

A NOAA-20 VIIRS True Color Red-Green-Blue (RGB) image viewed using RealEarth (below) also showed the hazy signature of dust-laden air.

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) image [click to enlarge]

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) image [click to enlarge]

===== 06 March Update =====

GOES-16 Shortwave Infrared (3.9 µm) image, with Metop-A ASCAT winds [click to enlarge]

GOES-16 Shortwave Infrared (3.9 µm) image, with Metop-A ASCAT winds [click to enlarge]

GOES-16 Shortwave Infrared (3.9 µm) images with overlays of Metop-A ASCAT winds around 0338 UTC (above) and 1607 UTC (below) revealed a secondary surge of Tehuano winds on 06 March. The highest wind speed at 0338 UTC was 44 knots, with 38 knots being measured at 1607 UTC.

GOES-16 Shortwave Infrared (3.9 µm) image, with Metop-A ASCAT winds [click to enlarge]

GOES-16 Shortwave Infrared (3.9 µm) image, with Metop-A ASCAT winds [click to enlarge]

GOES-16 Shortwave Infrared images (below) were useful to monitor the spread of cooler water (shades of yellow) as the strong surface winds induced upwelling — especially since the resulting strong gradient in water temperatures was falsely interpreted as cloud by the GOES-16 Sea Surface Temperature product.

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-17 and GOES-16 Visible images (below) showed how the swath of Tehuano winds had spread out toward the south and southwest compared to the previous day.

GOES-17 (left) and GOES-16 (right) "Red" Visible (0.64 µm) images, with plots of surface wind barbs (speed in knots) [click to play animation | MP4]

GOES-17 (left) and GOES-16 (right) “Red” Visible (0.64 µm) images, with plots of surface wind barbs (speed in knots) [click to play animation | MP4]

In contrast to the previous day, the GOES-16 Dust Detection product (below) showed a larger coverage of dust on 06 March — with significantly more Medium Confidence areas.

GOES-16 "Red" Visible (0.64 µm) images + Dust Detection product [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images + Dust Detection product [click to play animation | MP4]

A Suomi NPP VIIRS True Color RGB image at 1930 UTC (below) showed the hazy corridor of Tehuano winds bracketed by rope clouds.

Suomi NPP VIIRS True Color RGB image [click to enlarge]

Suomi NPP VIIRS True Color RGB image [click to enlarge]